In my book 1 st thing on M12's is real simple. Open the action see the joint between the chamber ring extension and the end of the barrel. See and feel if the joint is TOTALLY smooth and can't feel it one little bit. If you can, hand it back and walk away. Too many people who have owned a M12 take it down to clean it and use an abrasive of some type to clean the barrel chamber leaving it slightly larger than the chamber extension ring, doesn't take much and every time you use high brass shell the hull expands out past the diameter of the chamber extension ring and sticks or at least makes for very sticky extraction. If a guy wants to polish a model 12 chamber it needs to be done from the muzzle slowly and carefully while the chamber ring extension and barrel chamber are together in 1 piece by a PRO. It's the only pump out there beside the 97 with this retarded system. MB
